Front Head Research Articles

Dynamics of a Thunderstorm Outflow

Abstract The kinematic and thermodynamic structures of a thunderstorm outflow are examined by means of dual Doppler radar analysis, mesonet, lower, and sounding data. The data were collected in the Denver, Colorado area during June 1984. The dual-Doppler analysis shows that the cold outflow is ducted beneath the PBL inversion. Along the gust front there is a narrow quasi-two-dimensional updraft. Kelvin-Helmholtz instability (KHI) developed along the top of the gust front head near the surface front, and propagated backwards, dissipating in the wake of the head region. An isothermal layer aloft appears to have limited billow amplification to the quasi-neutral layer below. The gust front's leading edge had numerous inflections which are believed to result from barotrophic instabilities. Small vortices develop at some of the inflection points. Detailed analysis of one such circulation shows evidence of the formation of two enhanced updrafts separated by an occlusion downdraft. These observations are the firs...

Acoustic and Associated Behavior of the Coneheaded Katydid, Neoconocephalus nebrascensis (Orthoptera: Tettigoniidae)

Males of the coneheaded katydid, Neoconocephalus nebrascensis (Bruner), produce calling, male/male contact (aggressive), precopulatory, and disturbance sounds. Males may produce solo calling sounds but usually their calling sounds are synchronous with those of nearby males. During paired synchrony, the leader male produces a longer phrase and begins his phrase before and ends his phrase after the follower. As interkatydid distance is shortened, followers shorten their phrases. Males continue to synchronize when close, even when touching. Eventually the follower ceases calling and moves away. If males are not singing, antennal contact of another male may elicit the contact song from either male. Contact songs consist of shorter phrases and longer phrase intervals than solo or synchronized calling. Short bursts of male calling during the day, the first phrases of solo calling, and the precopulatory song are similar to contact songs except that the latter include short, clicklike sounds following some phrases. Such clicks are characteristic of male/male interactions in other katydid species. The disturbance sound is a single click produced during closing of a male's wings in response to tapping on a male's cage, movement of a male's perch, and before flight or hopping. Precopulatory songs are only elicited following antennation of a virgin female, contain no clicks, are produced by previously calling or silent males, and appear softer than other sounds. As in most strictly nocturnal singing orthopterans, physical fighting is rare. Fighting consists of raking with front legs, abdominal raking (performed in the parallel and opposite position characteristic of attempted copulations of females), and head butting, which may include biting without injury. Occasionally, males and females will tremulate (body shake) during male/male and male/female interactions.

Response of a human head-neck model to transient saggital plane loading

A reproducible, synthetic replica of the human head and neck system utilizing a water-filled cadaver skull mounted on fiberglass-reinforced resin vertebrae and supported by passive silicone rubber muscle and ligament elements has been constructed. Contact force, head accelerations, disk pressures and intracranial pressure responses to conditions of transient saggital plane pendulum loading have been ascertained. Front and rear head impacts as well as excitation of the entire system through its rigid base were effected. Input energies ranging from 0.0089 N m to 4.63 N m were employed resulting in head accelerations up to 180 g.

Lifesaving Releases---How Effective?

This study was designed to investigate how well lifesavers are able to remember and apply release techniques. Thirty lifesavers were filmed underwater while executing releases from front, rear, and wrist holds. Neither level of lifesaving qualification nor current lifeguard status nor date of lifesaving training, nor order in which the releases were executed systematically influenced performance. Lifesavers found the rear and wrist holds more difficult to break than the front head hold. Release techniques requiring several movements and accurate application of leverage principles to rotate the victim were poorly performed. Simple thrusting-type extension movements were more easily retained and better executed than the more complex releases.

The length of input data buffers in real time data acquisition systems

A real time data acquisition system is considered which has input data buffers between the external world and the front head microprocessor. The length of these buffers is analyzed for different data arrival and data collection distributions.

水中遠隔魚群探知機によるtrawl網口の観測

Some field experiments on board a two-boat trawler were made with an under-water echo-sounder of 200 kHz in the East China Sea in November, 1973. Throuthout the experiment, the three transducers were tightly fixed onto the three respective positions, i. e., the center and both ends of the front head rope of the square part of the trawl net. Thus, three series of echograms from fish schools, which pass through under the respective transducers, were drawn separately on an echo chart during trawling at a speed of 4 knots. The interrelation between the number of fish traces on the respective echo charts and the catch per haul were considered acoustically and statistically as follows: 1. The amount of fish school that passes into the trawl net along each sides near the wing net at the net mouth, might be about 26% more than that center part. 2. The highest correlation coefficient of catch per haul among respective number of fish, estimated from three series of echo charts per haul, was found to be 0.72 for that from the center transducer. 3. The author suggests that it may be possible for the transducer in such a system to be attached onto the center of the head rope to predict the amount of trawl catch.